Lucas 2FP pump

[ALAN COCHRANE]

Hi Everyone

The E-Type has been in dock since the replacement fuel pump failed at a Borders Car Show five weeks ago. Since then I've been waiting for SNGB to replace it but they're apparently having issues with the latest batch.
So I've decided to take a look at the original Lucas 2FP pump and see if I could get it working again.
The brushes looked really worn but after giving everything a thorough clean, it burst into life again. Happy days or so I thought. The pump doesn't appear to be pumping. I placed the pickup pipe in a tub of water and despite whirring away enthusiastically nothing appeared out of the exit pipe.
I've blown the pump through with an air line and it appears to be clear. When I initially dismantled it I noticed that petrol had been leaking into the motor housing.

Any thoughts as to why the pump should not be pumping?

Cheers

Alan

[cactusman]

The pump is a vane pump with a rotating impeller disc so unless it has become detached from the motor it should pump. It is intended to be more or less submerged so does not suck well at all. Other possible is that the relief valve is stuck open.

[ALAN COCHRANE]

Julian

You may have hit on the answer. I only dipped it into a tub with about two inches of water in it. I'm assuming the pump needs to be primed with fuel to operate or conversely relies on the fuel pressure being above a certain level, hence the submerged requirement.
The impeller at the bottom rotates freely under power and is undamaged so that doesn't seem to be the problem. The relief valve appears to be intact and the spring and ball bearing are in good nick. I might try adjusting it and see if that makes a difference.
I'll try submerging the pump in a bucket of water and see what happens. I'd dearly love to get the car back on the road as soon as possible.

Cheers

Alan

[Gfhug]

Alan, others might correct me, but after trying it on water, clean it out. Some pumps use the fuel as a lubricant (don't know if this one does) and you won't want water left in after your test.

Geoff

[ALAN COCHRANE]

Geoff

Good point. That may explain why there was evidence of petrol in the motor itself. I will blow the pump through with an air line once I've finished. Fingers crossed that it all works.

Cheers

Alan

[ALAN COCHRANE]

Well dunking the pump into a bucket of water did the trick. Once submerged it pumped water quite happily. So I've now got a working fuel pump for the first time in 5 weeks.
I ordered a new set of brushes so will wait until these arrive before refitting the pump. The design does indeed seem to utilise the pumped liquid as a coolant for the motor. The pump was full of water even after being submerged for less than a minute.

Cheers

Alan

[ysmalkie]

I thought I would revive an old thread.

I managed to purchase a NOS 2FP few years back for my e-type.

Once I finalny cleared all obstacles to install the fuel tank, I wanted ot fit the pum and test it - unfortunately it did not work.
I took it out on a bench, and all it could do was to pump the fuel about 10cm up the pipe..

So, I too apart the impeller housing, all was good and moving.

Then I opened up the valve, and to my surprise.. there was no valve!



Seems someone in '66 forgot to fit the ball and the spring.

Thankfully I had if from my old pump:



And it tested fine:




However I have one question remaining the polarity:
- I will change my car to negative earth. Is there anything I should do to the pump?
I know I have to change the connections, but it will not impact the earthing of the pump itself, am I right?

Tadek

[mtnjag]

When I got my E it had been in parked storage for about 12years, the pump wouldn't move. Pulled it, cleaned it, bought a backup new submersible and have been using the original for 35 years. The trunk smells like gas a bit but all is good.

[bitsobrits]

Fuel smell in the trunk may well be related to the tank vent pipe or slight weep from the main filler hose connection. Unless the pump or associated tubing is leaking, that probably is not the source of the fuel smell.

Lot's of posts here if you search for 'fuel smell in the boot' (or trunk).

[mtnjag]

Sniff tests takes it to harness from pump. Gasket to tank is good, venting and lines tight and dry.

[Geoff Allam]

Tadek, when I converted my 3.8 to negative ground I neglected to switch the fuel pump wires and it only ran till the carbs were dry and then stalled. I switched the wires, it started and I did not have to do anything more to it.

[ysmalkie]

Thanks - yes changing the wires is understandable, as otherwise it would run in the opposite direction.. :-)

However, as the pump body is earthed to the car, the body of the fuel pump becomes now negatively earthed, but I guess since the wires are reversed too, it will not cause an issue.

Tadek

[Geoff Allam]

No. There was no issue with that on mine.

[cactusman]

The wires are isolated from the pump body....Or should be....the body is earthed to present static build up presumably. Wise to do a continuity test to make sure....with both pump wires isolated there should be high resistance between either wire and the pump body. A spare I have in a box measures around 2 million ohms between either one of the leads and case....a pump in a tank of fuel will show a lower resistance I would imagine but still thousands of ohms from wires to case...resistance between the two leads will be much lower....the one in a box measures around 4 ohms...

[MarekH]

When I initially dismantled it I noticed that petrol had been leaking into the motor housing.

So testing it in a bucket of water wasn't really a very good idea, was it? You should have tested it using an inert fluid, rather than one which might conduct electricity.

You wouldn't check whether the cooker is on by lighting a match and having a look......

kind regards
Marek

[tinworm]

Parrafin or diesel work well to test . The internal parts of the pump run in fuel - it cools and lubricates the working parts . Most important part is the gauze in the bottom of the pump - there must be no holes in this item and the only repair is to substitute the case for another.
I find it is a very good and long lasting pump - is there anyone supplying the O ring seals at the moment?

Barrie

[ysmalkie]

You mean the seals for the pump?
They are square.

[cactusman]

Bizarrely the motor is, I think, actually full of fuel when operating....there is a small aperture in the casting that connects the motor to the fuel rail...as there is no air there can be no ignition and I guess the fuel provides some lubricant property and obviously aids cooling. The pump must not be tested using water and obviously pumping petrol is extremely unwise but paraffin is perfect for testing.

[MarekH]

The standard Bosch centrifugal pumps as used in the XJS are full of fuel and lack of fuel, or even simply too hot fuel, will kill the pump as it will overheat without "coolant" continuously flowing through it. The is no risk of fire as there is no air for the fuel to burn in, notmuch scope for spark at low current/voltage and even if there were air, it'd have to be within a narrow air:fuel ratio band to support combustion.

Using water isn't a good idea because eventually the innards will rust out and be the cause of multiple failure modes. Neither do you want to risk shorting out any electrical contacts during bench testing as smoke will escape if you do, there usually being no fuse in such a situation.

Working outside on a cold day with petrol is safer than people think:- it is the small amount of petrol vapour mixing with air on top of the surface which is the primary concern rather than the liquid itself and liquids like diesel and paraffin are even less volatile than that.

kind regards
Marek